To establish the pathophysiological basis and diagnostic significance of velocity waveform (VWF) analysis, we are investigating the relationship of the VWF to various hemodynamic conditions. A protocol has been established with a canine model which allows for an accurate, quantifiable method for producing progressive arterial stenosis, as well as variation in such factors as heart rate and peripheral vascular resistance. A NOVA computer system is being used to analyze the data, using various established methods of waveform analysis (e.g., Fast Fourier transforms, multidimensionsl analysis). This experimentation will lead to the development of a microcomputer system dedicated to the receipt interpretation, and output of VWF data. In order to improve the quality and reproducibility of VWF recordings, vaious new probe designs are being tested and compared as to their ability to maximize Doppler signal strength. The data base capabilities of an in-house TANDEM computer is providing an extensive capability for carrying out retrospective study of patients seen in the Vascular Diagnostic Laboratory. Statistical analysis of the discriminatory ability of carotid velocity waveform analysis as compared to other "state-of-the-art" noninvasive methods, is being employed in order to better our understanding of the efficacy of these techniques. Similar studies are being carried out for diagnostic techniques used in the detection of lower extremity disease.